In the application of labels to cylindrical containers, it is generally desirable to avoid the application of glue to the entire backside of the label. Applying glue to the entire backside of the label uses excessive quantities of glue and frequently causes blistering and/or wrinkling of the label. It is therefore generally desirable to apply glue to the label only along two opposing edges.
A method and apparatus for semi-automatically applying labels to cylindrical containers in such a way that only two opposing edges are contacted with glue is described in U.S. Pat. No. 3,278,359 issued to John G. Wesley in 1966. The Wesley patent provides an apparatus which takes a label from a label repository and brings that label into contact with a glue-retaining surface and then applies the label to a cylindrical container. After the label comes into initial contact with the glue-retaining surface, the label is separated from the glue-retaining surface by reciprocating lifting fingers so that glue is not applied to the central portion of the label. The fingers then retract so that glue is applied to the trailing edge of the label.
The Wesley patent method and device is not entirely satisfactory, however. The reciprocating lifting fingers and the associated timing mechanism and solenoid switches must be maintained in precise adjustment or the glue will be mis-applied to the label. Such precision is difficult to maintain in reciprocating machinery being operated day in and day out. Furthermore, in the Wesley apparatus, the timing of the lifting fingers must be accurately reset every time labels of different lengths are used in the machine. In short, the Wesley patent apparatus is expensive to manufacture, difficult and expensive to maintain and awkward and inefficient to operate.
Therefore, there is a need for a semi-automatic labelling method and machine capable of consistently metering glue to opposing edges of a label without the necessity of precisely timed reciprocating lifting fingers.
Also, there is a need for such a method and machine which is less expensive to manufacture, maintain and operate than the method and machine described in the Wesley patent.